Magnetic contact



July 31, 1945. VA,

MAG IiETI C CONTACT Filed April 26, 1943 Patented July 31, 1945 MAGNETIC OQNTACT Anthony H. Lamb, Hillside, N. 1., assigns: to Inetrnm Weston Electrical ent Corporation.

Newark, N. 1., a corporation of New Jersey Application April 28, 1943, Serial No. (84,611

Claims. (Cl. 200-168) This invention relates to magnetic contacts for use i sensitive instrument type relays, and particularly to a permanent magnet contact assembly including a pair of spaced pole pieces of opposite polarity ior simultaneous, or substantially simultaneous, engagement by a magnetic material rider on the contact arm of the relay.

Relay contact systems of this general type are described and claimed in my prior Patent No. 2,193,731, March 12, 1940, "Relay contact. The double contacts may be electrically connected, or they may be insulated from each other, as illustrated in the patent. The contact elements described inthe prior patent were miniature bar magnets of material of high coercive force, and the excessive hardness oi such materials presented some difilcultles in the machining and assembly of the twin contacts.

Objects of the present invention are to provide magnetic contact assemblies for use in sensitive relays, the assemblies comprising small permanent magnets and associated pole pieces of a softer magnetic material that constitute the contact surfaces ior'engagement with a cooperating magnetic material contact on the relay contact arm. An object is to provide a magnetized twin contact assembly of economical construction for use in relays, the assembly comprising a permanent magnet of plate or miniature bar form and associated contact polar extension of iron or other relatively soft material of high permeability.

These and other objects and the advantages of the invention will be apparent from the follow-- ing specification when taken with the accompanying drawing in which: v Fig, l is a schematic fragmentary view, in perspective and on an enlarged scale, oian instrument type relay including a magnetic contact assembly embodying the invention;

Fig-2 is a plan view of the relay contacts;

Fig. 3 is a vertical section as taken on line 3I of Fig. 2;

Figs. 4, 5 and 8 are, respective y fr gmentary perspective, plan and vertical section views of another torm of relay contact construction;

Fig. I is a side elevation of a modified form ofa contact assembly such as shown in Pig. 3: and

Fig. 8 is an enlarged sectional view or a contact assembly in which the polar extensions are insulated from each other.

In Fig. 1 cl thedrawing, the reference numeral I identifies the coil element oi a relay moving system that includes a pointer I carrying a small ylindrical rider I oi sott iron or other magneticmaterial. The cooperating, relatively stationary contact surfaces are the rounded ends of small pins I, I of soft iron or the like that extend at right angles to and are the pole pieces of a small permanent magnet I of block or miniature bar form. The contact assembly is carried by a bracket 1,

oi. brass or other non-magnetic material, that is secured to the scale plate I by screws I. The pole pieces I, I are threaded into the flanged end of bracket I, and the magnet I is secured to the inner face of the end flange by cement or solder II.

The controlled or relay circuit includes a current source II and load I! connected between the relay pointer I and the bracket I. The polar extensions I, I may be of different length, as explained in my prior patent, to limit the arcing at contact separation to the longer polar extension I.

The main axis of the permanent magnet I may be arranged parallel to the scale plate I by turning the end of pointer 2' upwardly at right angles to locate the axis or the soft iron contact I in the plane of symmetry between the polar extensions I, I. This construction, as illustrated in Figs. 4-6, locates both soft iron contacts I, I at the same distance from the main instrument magnet, not shown, and the contacts therefore are equally affected by the leakage flux oi the main magnet. The construction of this contact assembiy is similar to that previously described except that, as shown in Fig. 8, the contacts I, I are not threaded into the bracket I. The contacts may be secured in the bracket by a force-fit or by swaging, or they may be cemented or soldered to the bracket. Cement or solder II secures the magnet I to the bracket 1 and against the ends or the soft iron contacts I, I.

It is also practical to solder or cement the contacts I, I directly to the magnet I, as shown in F18. 7. and to solder or cement this contact assembly-to the outer lace oi the bracket I.

One or both of the iron contacts may be insulated from the magnet I and bracket 1, by a thin disk II of insulation at the base of the contact and a bushing II oi insulation. Circuit connections may be made to the contacts I, I by soldering leads II directly to them.

The magnetic contact assemblies are to be employed in sensitive instrument type relays, such as described in the prior patent. in which some form or pusher arm or electrical resetting system is provided to overcome the magnetic attraction oi the engaged contacts. The magnet may be oi small size when materials 0! high coercive force,

66 such as "Alnico." are employed and, in one satismagnet, and pole nieces oi soft iron c factory construction, the magnet was approxi matel 0.060 x 0.080 x 0.160 inch. The miniature bar magnets may be manufactured economically as they are merely small blocks that may be cast, pressed from powdered metals or cut from the bar stock and, if necessary or desired, may be readily ground to the required shape and size.

The small size of the contemplated contact assemblies indicates the difllculties previously encountered in shaping and mounting two magnets of exceedingly hard metal. The soft iron con-- tactelements of this invention may be readily formed to desired shape a. rd size by any of the simpler metal working processes, and they can be accurately mounted upon the bracket or directly upon the magnet by economical assembly processes.

It is to be understood that the invention is not limited to the particular construction herein shown and described, and that there is sir-ti r able latitude in the design and courts the contact assembly within the scope vention as set forth in the following: cl

I claim:

I. A twin contact assembly tor use in a c tive instrument relay of the magnetic col type; said assembly comprising a mi parallel relation from the opposite bar magnet, and means including a ing an end flange supporting said Ill pole pieces in fixed assembled relatior net being attached to a face of said binder- 2. A twin contact assembly comprising a supporting bracket of non-magnetic material, twin contacts of magnetic material of low retentivity secured to said bracket, said contacts being of pin form and extending substantially through said bracket from one face thereof, and a miniature bar magnet secured to the opposite face of said bracket with its poles adjacent the inner ends 01' the respective twin contacts.

3. A twin contact assembly of the magnetic type comprising a bracket of non-magnetic material, a miniature bar magnet secured to said bracket, and contact members'oi pin iorm constituting polar extensions of the magnet, said contact members being individually secured to and supported by said bracket.

4. A twin contact assembly for use in a sensitive instrument relay of the magnetic contact type; said assembly comprising a miniature bar maunet, and pole pieces oi soft iron extending in parallel relation. irom the opposite ends of the bar magnet and having outer ends for cooperation with a movable contact oi soi't iron, bracket and means scouring saitl magnet to one face oi thz bracket, said nieces extending into th! itsitc i lot claret and salt 

